In the commonly-assigned, co-pending application entitled "Safety Control System for X-Ray Scanner", filed concurrently herewith, there is disclosed a safety control system for a computerized tomographic X-ray scanner of the type wherein a source of radiation and a detector means are mounted for movement on the opposite sides of a medium in order that the radiation passes through successive planar sections of the medium and is attenuated and detected to give an output. According to the system disclosed in the noted application, the safety control includes means responsive to the rate of movement of the source of radiation and the detector together with blocking means which are actuated to block the flow of radiation from the source when the rate of movement of the radiation source is below a predetermined minimum.
The noted system allows the X-ray tubes to be maintained under operating voltage and current throughout the examination procedure. Additionally, the system acts to prevent excessive X-ray exposure by the patient being scanned or the operating personnel even if the apparatus for moving the source malfunctions.
In the specific embodiment disclosed in the noted application, the blocking means comprises a flat plate shutter formed from lead. The flat plate shutter is mounted for sliding movement transverse to the X-ray tube outlet aperture through a direct connection with a linear solenoid. Although this particular arrangement is generally satisfactory, its speed of actuation and reliability is less than desirable in the safety system of the type under consideration.